1. Field of the Invention
The present invention relates to annular bore seals for use in pipe connectors and swivel joints, among other devices.
2. Description of Related Art
Bore seals are used to provide a fluid-tight seal between adjoining pipes or members of swivel joints. U.S. Pat. No. 4,930,791, which is owned by the assignee hereof, discloses a bore seal assembly mountable within a seal pocket formed in the adjacent ends of the pipes to be sealed. This bore seal assembly comprises a cylindrical seal sleeve having a pair of annular sealing lips for sealing against corresponding sealing surfaces formed in the seal pocket, a cylindrical finger spring mounted within the bore of the seal sleeve for urging the seal sleeve against the seal pocket, and a cylindrical wear sleeve mounted within the bore of the finger spring to protect the seal sleeve and finger spring against erosion and hold the entire bore seal assembly together. The finger spring comprises an annular central section and a plurality of fingers extending axially therefrom around the entire circumference of the finger spring. In addition, the wear sleeve includes an annular rib extending radially outwardly from the wear sleeve for engaging the central section of the finger spring. In this manner, the fingers of the finger spring are permitted to flex radially inwardly adjacent the central section as the bore seal assembly is installed and impart a preload force which urges the sealing lips against the sealing surface of the seal pocket.
In this prior art bore seal assembly, the seal sleeve is constructed of a non-metallic material, such as Teflon.RTM., and the finger spring and wear sleeve are typically made of metal. When the bore seal assembly is exposed to very low temperatures, for example -100.degree. F., it has been discovered that the seal sleeve will contract against the finger spring and the wear sleeve and cause the fingers to yield adjacent the central section. As a result, the fingers are unable to maintain the preload force between the sealing lips and the sealing surface and the seal will leak.